Asthma, an inflammatory lung disease which causes chronic airflow obstruction, has a significant impact on the public health. There is mounting evidence that, in a subset of patients, pulmonary infection with mycoplasma and chlamydia is associated with chronic asthma. This study is designed to test the hypothesis that chronic infection with Mycoplasma pneumoniae or Chlamydia pneumoniae species is a risk factor for the development or worsening of asthma. A cohort of subjects with a history of clinically- and radiographically- evident M. pneumoniae and C. pneumoniae infection approximately nine years ago has been identified. All subjects in this cohort were tested for active mycoplasma or chlamydia infection with culture and polymerase chain reaction analysis of respiratory tract secretions, as well as serology. These patients will be studied using a respiratory symptoms questionnaire to determine the prevalence of asthma in this cohort nine years after the exposure. Following the questionnaire component of this study, additional testing will be performed on a subset of the cohort to further describe the clinical, physiologic, inflammatory and microbiologic characteristics of these patients. This series of investigations is designed to identify the importance of atypical bacterial infection to the development and clinical phenotype of asthma. An understanding of the association between mycoplasma and chlamydia species and asthma is critical to furthering our knowledge of asthma pathogenesis and provides the foundation on which interventions aimed at primary prevention may be based. The identification of infection as a risk factor for chronic asthma would be a significant advance in our ability to predict which patients have an increased likelihood of developing asthma and would facilitate the design and implementation of targeted attempts to reduce asthma incidence. The investigations described herein will be conducted as part of a comprehensive career development program in the methods of patient-oriented research. With this award, the candidate will become educated in the methods of patient-oriented research as part of a Master in Public Health degree program at the Harvard School of Public Health and will then apply the skills learned in the didactic setting to the implementation of this research protocol. The candidate is intent upon using this award to support a career development program that will ensure his success as an academic physician-scientist with a focus on patient-oriented research in diseases of the lungs.